1. Field of the Invention
The present invention relates to high-speed fire protection/suppression systems and, more particularly, to fast response fluid flow control nozzles incorporating a frangible element that is designed to be ruptured to release said material.
2. Description of the Background
The ongoing development of increasingly hazardous (i.e. energetic or explosive) materials requires concurrent improvements in the safety systems associated with their handling and storage. High-speed fire protection/suppression systems represent one of the most important safety systems associated with those evolving materials. High-speed fire protection/suppression systems take a number of forms. Common forms include (1) fixed pipe pilot-actuated spraying/sprinkler systems incorporating poppet valve-based nozzle assemblies and (2) pressurized containers of fire extinguishing/suppressing material (e.g. water) in combination with some means of fire detection. As one might expect, both forms possess certain pros and cons.
Pressurized containers have been historically used for the discharge of fire suppression agents in explosion suppression systems. Testing conducted by the Fire Research Laboratory at Tyndall Air Force Base has demonstrated that a pressurized container-based system, in this case a spherical container, can provide a significantly faster response time, in discharging a fire extinguishing/suppressing material to control various fire-related hazards, than a pilot-actuated spraying/sprinkler system. However, the limited, or finite, volume of fire extinguishing/suppressing material present in a pressurized container-based system, as opposed to the essentially unlimited supply available with a fixed pipe pilot-actuated spraying/sprinkler system, can be problematic. Additional deficiencies of pressurized container-based systems include (1) their typically bulky size/shape, (2) the significant cost and effort required to rearm/refill them, (3) their inability to be utilized/deployed in areas of limited size or accessibility, and (4) their initial purchase price.
The fast response time of a pressurized container-based system is generally provided by a fluid flow control valve incorporating a frangible element (e.g. a disc) and some means for rupturing that element upon the detection of a fire. The present invention is not the first to address the issue of fast response fluid flow control devices for fire protection/suppression systems. For example, U.S. Pat. No. 5,647,738 to Chatrathi et al., U.S. Pat. No. 5,458,202 to Fellows et al., U.S. Pat. No. 5,232,053 to Gillis et al., U.S. Pat. No. 5,031,701 to McLelland et al., U.S. Pat. No. 4,006,780 to Zehr, and U.S. Pat. No. 3,834,463 to Allard et al. disclose a variety of means for releasing the flow of a fire extinguishing/suppressing material via the rupturing of a frangible element.
U.S. Pat. No. 5,647,438 to Chatrathi et al. discloses an explosion suppressant dispersion nozzle for dispersing suppressant material from a pressurized suppressant storage vessel to a protected zone or room upon the rupturing of a frangible element by an actuator.
U.S. Pat. No. 5,458,202 to Fellows et al. discloses a pressurized extinguishant release device with a penetrator affixed to a rolling diaphragm. The penetrator is positioned above a frangible membrane that encloses a pressurized extinguishant. Heating of a liquid filled sensor tube to a certain temperature will cause vapor pressure to push against the diaphragm, causing a shear pin to fail, and propel the penetrator into the membrane and thus allow the extinguishant to flow.
U.S. Pat. No. 5,232,053 to Gillis et al. discloses an explosion protection system including a container with a discharge outlet adapted to contain an explosion suppressant under pressure, a frangible member covering the discharge outlet, an explosive charge disposed in the container adjacent to the frangible member and adapted to create explosive forces that rupture said member, and a somewhat compressible explosion suppressant retained under pressure.
U.S. Pat. No. 5,031,701 to McLelland et al. discloses a suppressant delivery and release nozzle structure for an explosion protection system. The nozzle is a reducing elbow, concentric or eccentric mounting a rupture disc at its small end. A selectively actuatable detonator housed in the nozzle adjacent the disc permits substantially instantaneous opening of the disc upon command for release and delivery of suppressant to a zone to be protected from an explosion hazard.
U.S. Pat. No. 4,006,780 to Zehr discloses a device for rupturing a pressurized cylinder containing a fire extinguishing product. When the temperature is high enough to melt a fusible link, a spring-loaded punch is forcibly propelled downwardly to rupture a frangible disc in the cylinder to allow the contents to be discharged.
U.S. Pat. No. 3,834,463 to Allard et al. discloses a sensitive sprinkler that includes a rupture disc valve positioned to block fluid flow through the flow path. An explosive squib is mounted in the fluid flow path upstream of the rupture disc so that when exploded an expansive gas directs a pressure through said fluid to rupture the disc. A fire detector assembly electrically activates the squib substantially immediately upon detection of a fire.
The ideal fire protection/suppression system would combine the fast response of a container-based system with the essentially unlimited extinguishing/suppressing material supply of a fixed pipe system. Unfortunately, due to the nature of fixed pipe fire protection/suppression systems, each of these prior art devices possesses certain limitations with respect to the specific needs addressed by the present invention. The Chatrathi et al., Gillis et al., McLelland et al., and Allard et al. patents incorporate the storage and use of an explosive device/detonator to rupture the frangible element. The use of any explosive device/detonator does provide the required activation speed of a system, however the type and size of the device being considered is essential as it may be exposed to highly energetic/explosive materials. Additionally, the Gillis et al. and Allard et al. patents operate in a manner that generates an omni-directional pressure wave that momentarily disrupts the outward flow of the fire suppressing material. With highly energetic/explosive materials, every fraction of a second counts and, therefore, any process that delays the outward flow of the fire suppressing material is one that must be eliminated. The Fellows et al. and Zehr patents disclose components used to rupture the frangible elements that are positioned within the flow pathway for the fire extinguishing/suppressing material. This configuration, in a best case scenario, results in a marginal occlusion of the orifice through which the fire extinguishing/suppressing material is meant to flow. In a worst case scenario, the orifice might become completely occluded.
Therefore, there remains a need for a fast response fluid flow control valve/nozzle incorporating a frangible element that is designed to be ruptured to release fire suppressant material from an essentially unlimited supply. While the use of an explosive or energetic actuator may be required to provide the required speed of activation of a system, significant consideration should be given to reducing the potential hazard. The fluid flow control valve/nozzle should also be scalable to provide for use in a variety of applications, fabricated of materials that provide the durability/longevity required by the nature of its use, capable of being retrofitted to existing fire protection/suppression systems, and economical to manufacture in order to provide for widespread use.